/*
    * Copyright (C) 2009 The Guava Authors
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.google.common.collect;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import com.google.common.primitives.Primitives;
  
  import java.io.Serializable;
  import java.util.Map;
  
  import javax.annotation.Nullable;
  
  /**
   * A class-to-instance map backed by an {@link ImmutableMap}. See also {@link
   * MutableClassToInstanceMap}.
   *
   * @author Kevin Bourrillion
   * @since 2.0 (imported from Google Collections Library)
   */
  public final class ImmutableClassToInstanceMap<B> 
      extends ForwardingMap<Class<? extends B>, B> 
      implements ClassToInstanceMap<B>, Serializable {
    
    /**
     * Returns a new builder. The generated builder is equivalent to the builder
     * created by the {@link Builder} constructor.
     */
    public static <B> Builder<B> builder() {
      return new Builder<B>();
    }
  
    /**
     * A builder for creating immutable class-to-instance maps. Example:
     * <pre>   {@code
     *
     *   static final ImmutableClassToInstanceMap<Handler> HANDLERS =
     *       new ImmutableClassToInstanceMap.Builder<Handler>()
     *           .put(FooHandler.class, new FooHandler())
     *           .put(BarHandler.class, new SubBarHandler())
     *           .put(Handler.class, new QuuxHandler())
     *           .build();}</pre>
     *
     * <p>After invoking {@link #build()} it is still possible to add more entries
     * and build again. Thus each map generated by this builder will be a superset
     * of any map generated before it.
     *
     * @since 2.0 (imported from Google Collections Library)
     */
    public static final class Builder<B> {
      private final ImmutableMap.Builder<Class<? extends B>, B> mapBuilder
          = ImmutableMap.builder();
  
      /**
       * Associates {@code key} with {@code value} in the built map. Duplicate
       * keys are not allowed, and will cause {@link #build} to fail.
       */
      public <T extends B> Builder<B> put(Class<T> key, T value) {
        mapBuilder.put(key, value);
        return this;
      }
  
      /**
       * Associates all of {@code map's} keys and values in the built map.
       * Duplicate keys are not allowed, and will cause {@link #build} to fail.
       *
       * @throws NullPointerException if any key or value in {@code map} is null
       * @throws ClassCastException if any value is not an instance of the type
       *     specified by its key
       */
      public <T extends B> Builder<B> putAll(
          Map<? extends Class<? extends T>, ? extends T> map) {
        for (Entry<? extends Class<? extends T>, ? extends T> entry
            : map.entrySet()) {
          Class<? extends T> type = entry.getKey();
          T value = entry.getValue();
          mapBuilder.put(type, cast(type, value));
        }
        return this;
      }
  
      private static <B, T extends B> T cast(Class<T> type, B value) {
        return Primitives.wrap(type).cast(value);
      }
  
     /**
      * Returns a new immutable class-to-instance map containing the entries
      * provided to this builder.
      *
      * @throws IllegalArgumentException if duplicate keys were added
      */
     public ImmutableClassToInstanceMap<B> build() {
       return new ImmutableClassToInstanceMap<B>(mapBuilder.build());
     }
   }
 
   /**
    * Returns an immutable map containing the same entries as {@code map}. If
    * {@code map} somehow contains entries with duplicate keys (for example, if
    * it is a {@code SortedMap} whose comparator is not <i>consistent with
    * equals</i>), the results of this method are undefined.
    *
    * <p><b>Note:</b> Despite what the method name suggests, if {@code map} is
    * an {@code ImmutableClassToInstanceMap}, no copy will actually be performed.
    *
    * @throws NullPointerException if any key or value in {@code map} is null
    * @throws ClassCastException if any value is not an instance of the type
    *     specified by its key
    */
   public static <B, S extends B> ImmutableClassToInstanceMap<B> copyOf(
       Map<? extends Class<? extends S>, ? extends S> map) {
     if (map instanceof ImmutableClassToInstanceMap) {
       @SuppressWarnings("unchecked") // covariant casts safe (unmodifiable)
       // Eclipse won't compile if we cast to the parameterized type.
       ImmutableClassToInstanceMap<B> cast = (ImmutableClassToInstanceMap) map;
       return cast;
     }
     return new Builder<B>().putAll(map).build();
   }
 
   private final ImmutableMap<Class<? extends B>, B> delegate;
 
   private ImmutableClassToInstanceMap(
       ImmutableMap<Class<? extends B>, B> delegate) {
     this.delegate = delegate;
   }
 
   @Override protected Map<Class<? extends B>, B> delegate() {
     return delegate;
   }
 
   @Override
   @SuppressWarnings("unchecked") // value could not get in if not a T
   @Nullable
   public <T extends B> T getInstance(Class<T> type) {
     return (T) delegate.get(checkNotNull(type));
   }
 
   /**
    * Guaranteed to throw an exception and leave the map unmodified.
    *
    * @throws UnsupportedOperationException always
    * @deprecated Unsupported operation.
    */
   @Deprecated
   @Override
   public <T extends B> T putInstance(Class<T> type, T value) {
     throw new UnsupportedOperationException();
   }
 }